# The AcquireImage Trigger Modes

The AcquireImage Trigger Mode parameter defines how the function will be activated to acquire an image. The parameter options can be divided into two categories: externally triggered and self-triggered.

Note: In Offline mode, regardless of the Trigger Mode setting, acquisitions can be initiated by pressing the Trigger Once button or pressing F6.

## Externally Triggered Modes

The externally triggered modes, Camera, Timer Interval, and Industrial Ethernet, all depend on an outside event to initiate image acquisition, and the subsequent job execution (which begins once the acquisition has been completed).

In this mode, acquisitions are "armed" at the end of the previous job cycle, and will be initiated immediately when the next trigger event occurs.

Any missed acquisition will be reported if the trigger event occurs while another acquisition is in progress, or if the delay period between a prior trigger and the initiation of its acquisition lapses. These missed acquisitions are tracked via either the Event function (setting the Trigger parameter to Acquisition Missed) or using the Configure Discrete I/O Lines to set an output line to Acquisition Missed.

Note: The Timer Interval trigger mode is unique because the event is delayed until the trigger is next "armed", so missed triggers never occur. In essence, the Timer Interval setting is not a direct requirement that a trigger happens every N ms. Instead, it's based on the model of triggering image acquisitions every N ms, or as soon as the prior job cycle completes, whichever is longer.

When the ApplyAcquisitionSettings function is being used, and an externally triggered mode is specified, changing a setting via the ApplyAcquisitionSettings function will not affect the next acquired image, because that acquisition has already been armed. The changed setting will not take effect until the subsequent acquisition.

For example, if acquisition N causes the spreadsheet to run and execute an ApplyAcquisitionSettings function, acquisition N+1 will use the old settings, and N+2, N+3, etc. will use the new settings.

While Online, you can force an acquisition to re-arm and therefore apply the changed settings to the next acquisition by pausing and un-pausing the vision system; this will abort the currently-armed acquisition (pause) and then arm again (un-pause).

## Self-Triggered Modes

The self-triggered modes, Continuous and Manual, refer to the fact that the start of the job cycle initiates image acquisition. In these modes, missed triggers are not reported, because the system will wait until the prior job cycle completes before initiating the next job cycle.

During Online mode, the Manual trigger is only initiated by using a WebPage with a Button element that has its Click Command property set to Tasks.InspectionTask.Run.

When the ApplyAcquisitionSettings function is being used with a self-triggered mode, settings changed via the ApplyAcquisitionSettings function will take effect immediately (i.e. acquisition N+1).